This invention relates, in general, to an apparatus and method for processing large diameter pipes, such as used in drilling and production of subsea oil and gas wells, and in particular, this invention is directed to an apparatus and method for cold forming (swaging) the ends of such large diameter pipes into tapered (cone shaped) sections as one step in forming of pin connectors.
Pin connectors to form a joint between large diameter pipes are used extensively in offshore drilling and production of subsea oil and gas wells. One use of such pipes is to connect them end-to-end to form a casing connection extending from a vessel on the surface of the water to the ocean floor. To form the connection, various taper angles and thread forms are used.
Such large diameter pipes typically range from 16" to 26" in diameter, have a wall thickness ranging from 0.438" to 1.00" and are typically over 40 ft. in length.
To form the pin on the ends of such pipes, the pipe ends are first provided with conically shaped sections and then these sections are provided with threads of any suitable thread form. However, the threads on such pipes can be severely restricted in scope by the allowed outer diameter tolerance, out-of-roundness, and the wall thickness tolerances. These result in lack of adequate thread length, lack of thread nose thickness, or both. Thus, current threaded pipe designs either compromise on the strength of the threads or require specially selected pipes.
It is an object of this invention to provide an apparatus and method which provides conical sections of adequate thickness and length for suitable threads so that there is no need to compromise the thread design or to be restricted in the selection of pipes to use.